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MHT CET 2023 (14 May, Shift 2) · Heat Engines, Refrigerators & Second Law

Heat Engines, Refrigerators & Second Law question from MHT CET 2023 (14 May, Shift 2)

Q28MHT CET 2023 · 14 MAY · SHIFT 2Medium

Heat Engines, Refrigerators & Second Law

An ideal refrigerator has freezer at a temperature of $-13^\circ\text{C}$ . The coefficient of performance of the engine is 5. The temperature of the air (to which heat is rejected) is

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Answer: (b)

Ideal refrigerator: $\beta = \frac{T_2}{T_1 - T_2}$ with $T_2 = -13^\circ\text{C} = 260$ K.
$5 = \frac{260}{T_1 - 260} \Rightarrow T_1 - 260 = 52$
$T_1 = 312\text{ K} = 39^\circ\text{C}$
So the answer is (b) $39^\circ\text{C}$ .

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